280 Annals of tlie South African Museum. 



posterior zone broad, with the pores more elongated than in the 

 anterior zone. Interporiferous zone with granules. Postero-lateral 

 poriferous zones similar to the antero-lateral but shorter, extending 

 to about four-fifths of the distance from the apex to the margin. 



Anterior interambulacra rising rapidly in front of the antero-lateral 

 ambulacra. Lateral interambulacra slightly convex. Posterior 

 interambulacrum forming a median rounded ridge. Interambulacra 

 with few small tubercles and many granules. The tubercles are 

 rather more prominent at the sides of the anterior furrow, and are 

 larger on the anterior part of the base, and closer together on the 

 plastron than elsewhere. 



Peristome oval, at about a fifth of the total length from the anterior 

 margin. Periproct large, oval, near the summit of the truncated 

 posterior end. Marginal fasciole well developed, broadest below the 

 periproct. 



Affinities. — In general form this species presents some resem- 

 blance to the smaller examples of G. anancliytis, Leske,* but the 

 anterior part of the test is more elevated, and the keels on the sides 

 of the anterior furrow are more prominent. 



Examples of this species were referred to Ilolaster indicus, 

 Forbes,! by Griesbach, although the marginal fasciole is seen 

 quite clearly in the specimens which he collected. 



Family SPATANGIDtE. 



Genus HEMIASTEE, Desor. 



Hemiastek Forbesi, Baily. 



Plate XXXIIL, figs. &, 9. 



1855. Hemiaster Forbesii, Baily, Q.J.G.S., xi., p. 463, pi. xii., fig. 1. 



Description. — Test of small or moderate size, sub-cordate. 



Length and breadth equal or nearly equal. Greatest breadth is 



anterior to the middle of the length. Posterior end truncated. 



Upper surface convex, deeply furrowed by the ambulacra ; with a 



rounded carina posteriorly. Lower surface flattened, but concave 



near the peristome. Greatest height behind the apical disc. 



Apical disc nearly central, depressed below the level of the 



* See, for instance, Cotteau and Triger, Echin. de la Sarthe (1860), p. 237, pi. li., 

 figs. 2-0. 



t Trans. Geol. Soc, ser. 2, vol. vii. (1846), p. 159, pi. xix., fig. 4. 



